A total of 12 healthy normal drug-naïve volunteers will be enrolled at McLean Hospital to participate in this 5-visit (1 screening visit, 4 study visits) double-blind, placebo-controlled study. Participants will be between 21 and 40 years of age, they can be either male or female, and there are no restrictions regarding ethnic background. Participants will have no past or current neurological or psychiatric disorders (including any substance abuse and/or dependence), no family history of alcoholism, no medical conditions that could affect drug disposition, and they will not be taking any medications. Participants also cannot have any MRI scanning contraindications (including pregnancy). They must be able to provide informed consent.